Chinese tech giant Xiaomi Corp will ratchet up its challenge to Apple by focusing on the high-end segment of the global smartphone market, according to company founder and chief executive Lei Jun , as the mainland’s major handset makers rush to fill the void left by struggling Huawei Technologies Co . “[We aim to] fully benchmark against Apple in [terms of] product and experience, and become China’s biggest high-end brand in the next three years,” Lei said in a post on microblogging platform Weibo on Tuesday, as he reiterated the company’s strategic goal to develop into the world’s largest smartphone…